There are known in the state of the art load protection systems having several functions, such systems generally enabling automatic stopping of the current when an abnormal state occurs. For example, it has already been known from the patent application FR 2 645 362 to integrate several functions within a single concept for a protection system enabling active and passive prevention. The arrangement described in this application comprises circuit breakers in a first unit acting on several phases of a principal circuit, such circuit breakers reacting to an overload current, the interruption mechanism being also coupled to an electromagnet permitting interrupt manoeuvres and closing down of the principal circuit. In a second unit, there is provided a current transformer for each of the phases, such transformer serving uniquely for the detection of a current flowing in the phase concerned. Moreover, such system comprises a means for production of signals coupled to the current transformers, automatic or remote controlled triggering means, means for communication with a central microcomputer and display means.
If this system has the advantage of proposing a set of integrated functions within a single arrangement, it is relatively heavy in components. In particular, the short-circuit protection and the stopping function in case of an anomaly in a predetermined parameter of such current require two different triggering mechanisms acting on the same pair of contacts. Next, the measuring function requires several units comprising current transformers which are structurally separated from the circuit breakers. This not only brings about an increase in the cost of construction, but complication during the assembly and a relatively substantial space requirement.
The invention has as its purpose to provide a protection system for at least one electric circuit which is more simple and less costly than that of the prior art cited hereinabove.